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192.168.1.100 / T106_DC / d7592ef3679300d5c01c3f754e38bac1f49d5591 / . / ap / app / iptables / extensions / libipt_TTL.c
blob: 0e2be0b6f4db2f0b34e2c57e0da718da07362c88 [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -0700[diff] [blame]1/* Shared library add-on to iptables for the TTL target
2 * (C) 2000 by Harald Welte <laforge@gnumonks.org>
3 *
4 * $Id$
5 *
6 * This program is distributed under the terms of GNU GPL
7 */
8#include <stdio.h>
9#include <string.h>
10#include <stdlib.h>
11#include <getopt.h>
12#include <xtables.h>
13
14#include <linux/netfilter_ipv4/ipt_TTL.h>
15
16#define IPT_TTL_USED 1
17
18static void TTL_help(void)
19{
20 printf(
21"TTL target options\n"
22" --ttl-set value Set TTL to <value 0-255>\n"
23" --ttl-dec value Decrement TTL by <value 1-255>\n"
24" --ttl-inc value Increment TTL by <value 1-255>\n");
25}
26
27static int TTL_parse(int c, char **argv, int invert, unsigned int *flags,
28 const void *entry, struct xt_entry_target **target)
29{
30 struct ipt_TTL_info *info = (struct ipt_TTL_info *) (*target)->data;
31 unsigned int value;
32
33 if (*flags & IPT_TTL_USED) {
34 xtables_error(PARAMETER_PROBLEM,
35 "Can't specify TTL option twice");
36 }
37
38 if (!optarg)
39 xtables_error(PARAMETER_PROBLEM,
40 "TTL: You must specify a value");
41
42 if (xtables_check_inverse(optarg, &invert, NULL, 0))
43 xtables_error(PARAMETER_PROBLEM,
44 "TTL: unexpected `!'");
45
46 if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX))
47 xtables_error(PARAMETER_PROBLEM,
48 "TTL: Expected value between 0 and 255");
49
50 switch (c) {
51
52 case '1':
53 info->mode = IPT_TTL_SET;
54 break;
55
56 case '2':
57 if (value == 0) {
58 xtables_error(PARAMETER_PROBLEM,
59 "TTL: decreasing by 0?");
60 }
61
62 info->mode = IPT_TTL_DEC;
63 break;
64
65 case '3':
66 if (value == 0) {
67 xtables_error(PARAMETER_PROBLEM,
68 "TTL: increasing by 0?");
69 }
70
71 info->mode = IPT_TTL_INC;
72 break;
73
74 default:
75 return 0;
76
77 }
78
79 info->ttl = value;
80 *flags |= IPT_TTL_USED;
81
82 return 1;
83}
84
85static void TTL_check(unsigned int flags)
86{
87 if (!(flags & IPT_TTL_USED))
88 xtables_error(PARAMETER_PROBLEM,
89 "TTL: You must specify an action");
90}
91
92static void TTL_save(const void *ip, const struct xt_entry_target *target)
93{
94 const struct ipt_TTL_info *info =
95 (struct ipt_TTL_info *) target->data;
96
97 switch (info->mode) {
98 case IPT_TTL_SET:
99 printf("--ttl-set ");
100 break;
101 case IPT_TTL_DEC:
102 printf("--ttl-dec ");
103 break;
104
105 case IPT_TTL_INC:
106 printf("--ttl-inc ");
107 break;
108 }
109 printf("%u ", info->ttl);
110}
111
112static void TTL_print(const void *ip, const struct xt_entry_target *target,
113 int numeric)
114{
115 const struct ipt_TTL_info *info =
116 (struct ipt_TTL_info *) target->data;
117
118 printf("TTL ");
119 switch (info->mode) {
120 case IPT_TTL_SET:
121 printf("set to ");
122 break;
123 case IPT_TTL_DEC:
124 printf("decrement by ");
125 break;
126 case IPT_TTL_INC:
127 printf("increment by ");
128 break;
129 }
130 printf("%u ", info->ttl);
131}
132
133static const struct option TTL_opts[] = {
134 { "ttl-set", 1, NULL, '1' },
135 { "ttl-dec", 1, NULL, '2' },
136 { "ttl-inc", 1, NULL, '3' },
137 { .name = NULL }
138};
139
140static struct xtables_target ttl_tg_reg = {
141 .name = "TTL",
142 .version = XTABLES_VERSION,
143 .family = NFPROTO_IPV4,
144 .size = XT_ALIGN(sizeof(struct ipt_TTL_info)),
145 .userspacesize = XT_ALIGN(sizeof(struct ipt_TTL_info)),
146 .help = TTL_help,
147 .parse = TTL_parse,
148 .final_check = TTL_check,
149 .print = TTL_print,
150 .save = TTL_save,
151 .extra_opts = TTL_opts,
152};
153
154void _init(void)
155{
156 xtables_register_target(&ttl_tg_reg);
157}